Friends, Foes, or Food: Among Cannibal Warrior Chimps

The chimpanzees stopped. Silently, each mouth parted into a grimace, teeth and gums exposed. They turned to one another and embraced, arms around each other’s shoulders and backs. Then they ran. I bolted after them, hugging my binoculars to my chest, ducking under branches and wriggling my way through vines that grabbed at me.

We came face-to-face with a neighboring group of chimpanzees: the formidable enemies who live to the south of the Ngogo community. Chimpanzees on both sides hooted and drummed the exposed roots of trees. The Ngogo males scattered, running back and forth screaming. The neighboring group of males continued to yell and cry as they retreated south. I followed Rollins, a slender-faced Ngogo adult male. He gave the trunk of a tree one last kick that echoed through the forest. The battle was over.

Male chimpanzees hug one another before encountering neighbors. (Photo by Aaron Sandel)

Chimpanzees are highly territorial, and the Ngogo chimpanzees are especially famous for their war-like behavior. They regularly go on patrols of their borders, walking in single-file lines as if on a covert military operation. Inter-group encounters can result in lethal aggression and at Ngogo this has lead to territorial expansion. This time there were no casualties in the face-off. But the neighbors of Ngogo are not always so lucky.

In early January a group of Ngogo chimpanzees—male and female—went on a patrol. As we reached the top of a valley, the males took the lead, leaving behind the females with their infants and juveniles. Suddenly, they became silent and stood upright on their back legs. They turned and hugged one another. Then they broke apart and sprinted down the hill. I ran after them. I heard a chorus of screams. When I caught up to them, they were in a pig-pile grappling over something. I saw Richmond, a hulking, one-armed male, emerge with a dead infant chimpanzee in his mouth.

In the moment before I reached them, the chimps must have surprised a neighboring female, and in a matter of seconds, ripped the infant from her arms. It is also possible that it was not a neighbor, but a fringe Ngogo female. Occasionally males commit infanticide on a group mate, especially if it is a female they rarely see and thus whose infant they probably have not fathered. But given how far west we were, it was likely a neighboring female, foolishly close to the edge of her community’s territory.

I watched as the males proceeded to share the infant’s carcass and devour the meat as they hurried back within the border of their own territory. While the group excitedly cannibalized the infant, they continued to act gently toward the infants from their own community. Some Ngogo infants even begged for the meat of the killed infant. Richmond ignored the tiny face of one infant, looking longingly at the meat, but he did share a large piece with other adults, including his younger brother, Hutcherson. I found this juxtaposition striking. How can chimpanzees so easily consider some individuals friends and others foes (and even food)?

Ngogo infant stares at the mangled hand of the killed infant, hoping for meat (photo by Aaron Sandel)
An Ngogo infant stares at the mangled hand of the killed infant, hoping for meat. (Photo by Aaron Sandel)

Chimpanzees are brutally violent when it comes their neighbors, but they display strong social bonds with group-mates. In fact, it is before moments of violence that friendship is so strikingly apparent. Chimpanzees hug each other or clasp hands for reassurance. While traveling in the unknown space between territorial borders, it is a life or death situation, and cooperation and support are crucial for survival.

Friends—which are determined by time spent traveling and grooming together—also support each other in the fight for status within the community. While less violent towards them, chimpanzees are nevertheless still quite aggressive toward group mates. Everyone cooperates against the common-enemy neighbors, but within the community alliances and rivalries are continually negotiated. In forging alliances, friendships are critical. A chimp may defend a group member one day, but fight against him the next. Friends, once formed, however, tend to be enduring allies.

Even then though, the distinction between friend and enemy is not always clear. A high-ranking male may groom the alpha male in the hopes of soon overthrowing him. The Godfather’s famous Machiavellian line, “Keep your friends close, but your enemies closer,” appears to apply to chimpanzees as well as humans.

Aaron Sandel watches a group of chimpanzees before they go on a patrol of their borders (photo by Nathan Chesterman)
Aaron Sandel watches a group of chimpanzees before they go on a patrol of their borders. (Photo by Nathan Chesterman)

The adolescent males who are the focus of my research are, for the first time, vying for dominance, helping to defend their territory, and trying to keep afloat amidst the real politik of chimpanzee life.

Adolescence itself is a kind of borderland: males are no longer dependent on their mothers but are not quite adults. Whether traveling at the edge of their territory or traversing the social world within their home range, friendships may play a key role in this liminal period, in this critical space in between. Whether they form friendships during this time remains unknown, and is the question that I am here to answer.

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Meet the Author
I am a PhD student in Anthropology at the University of Michigan. I write from Ngogo, in the center of Kibale National Park in Uganda, home to 200 chimpanzees, the subjects of my dissertation. A National Geographic Young Explorers grant in 2013 got me through the angst of finalizing a dissertation project. Now, I study angst, or at least the closest thing to it: friendship and the transition to adulthood in male chimpanzees. When I’m not focused on following a chimpanzee, my forest daydreams include opening a vegan burrito restaurant in a rural Ugandan village and making a documentary about an old fig tree.